diff --git a/libcxx/include/bit b/libcxx/include/bit
--- a/libcxx/include/bit
+++ b/libcxx/include/bit
@@ -116,14 +116,13 @@
     else
     {
         int __ret = 0;
-        int __iter = 0;
         const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
-        while ((__iter = __libcpp_ctz(static_cast<unsigned long long>(__t))) == __ulldigits)
+        while (static_cast<unsigned long long>(__t) == 0uLL)
         {
-            __ret += __iter;
+            __ret += __ulldigits;
             __t >>= __ulldigits;
         }
-        return __ret + __iter;
+        return __ret + __libcpp_ctz(static_cast<unsigned long long>(__t));
     }
 }